Extensive Expansion of the Speedy gene Family in Homininae and Functional Differentiation in Humans

Background: The cell cycle plays important roles in physiology and disease. The Speedy/RINGO family of atypical cyclins regulates the cell cycle. However, the origin, evolution and function of the Speedy family are not completely understood. Understanding the origins and evolution of Speedy family would shed lights on the evolution of complexity of cell cycles in eukaryotes. Results: Here, we performed a comprehensive identification of Speedy genes in 258 eukaryotic species and found that the Speedy subfamily E was extensively expanded in Homininae, characterized by emergence of a low-Spy1-identify domain. Furthermore, the Speedy gene family show functional differentiation in humans and have a distinct expression pattern, different regulation network and co-expressed gene networks associated with cell cycle and various signaling pathways. Expression levels of the Speedy gene family are prognostic biomarkers among different cancer types. Conclusions: Overall, we present a comprehensive view of the Speedy genes and highlight their potential function.